Ozone has an extremely high standard oxidation-reduction potential at 25° C. of 2.07V, and its oxidation potential is the next strongest after fluorine. Therefore, an ozone treatment is conventionally performed by taking advantage of this oxidation potential in various fields of semiconductor-cleaning, food-cleaning (sterilization), water-purification, and the like.
In addition, since ozone produces only oxygen by decomposition thereof, and therefore ozone is environmentally friendly, use of ozone has tended to increase in recent years.
A method for improving effects of such an ozone treatment usually involves increasing the amount of ozone used. However, an increase of the amount of ozone used directly leads to an increase in treatment cost. In addition, the amount of non-utilized de-absorbed ozone, that is, ozone released in air without being absorbed in water when performing the treatment while supplying ozone into water, will be increased. An increase of de-absorbed ozone not only leads to an increase in cost required for the treatment but also heightens concern about work safety. In Japan and many other countries, in regard to the ozone concentration, a value of 0.1 ppm (=0.2 mg/m3) is employed as a work environment standard considering work safety. Thus, there is a limit to increasing the amount of ozone used.
For solving such problems, Patent Document 1 discloses a sterilizing method including the use of ozone together with hydrogen peroxide as a method for obtaining a high treatment effect while reducing the amount of ozone used. Patent Document 2 discloses a sterilizing method including immersing food alternately into an ozone solution and an organic acid solution and/or an alcohol solution.
However, these methods require another treatment step to be performed in addition to the step of treating with ozone, and thus the process becomes complicated.
Further, as the method for improving efficiency of the ozone treatment, a method of using ozone with an organic substance has been proposed.
For example, Patent Document 3 discloses a germicidal detergent composition containing ozone and a surfactant, the germicidal detergent composition enhancing germicidal effects when the substance to be treated is immersed therein. The germicidal detergent composition is intended to supplement washing effects on oily components with a surfactant, and also to employ the residual effect of ozone.    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. H11-226579    Patent Document 2: Japanese Unexamined Patent Application, First Publication No. H3-164155    Patent Document 3: Japanese Unexamined Patent Application, First Publication No. H6-313194